1. Field of the Invention
This invention relates to magnetic video tape apparatus, and particularly to an overload protection circuit operative during loading and unloading operations of the tape.
2. The Prior Art
Magnetic video tape apparatus, such as that disclosed in U.S. Patent application Ser. No. 354,992, filed Apr. 27, 1973 and issued June 28, 1974 as U.S. Pat. No. 3,821,805, and assigned to the assignee of the present application, includes means for withdrawing a loop of tape from the cassette by means to a tape engaging assembly. The assembly includes a support ring that rotates about a tape guide drum in which a magnetic head assembly is installed. The support ring has a pinch roller and several tape guide pins and is driven by a direct current (DC) motor.
In the apparatus described in the aforesaid U.S. patent, there is a chance of malfunctioning of the apparatus during the tape loading or unloading operations whereby movement of the support ring may be prevented, for example if the magnetic tape that has been withdrawn becomes tangled in the mechanism. Other problems can arise to interfere with free rotation of the DC motor. In that event, the DC motor used as a driving source for the support ring may be overloaded. The effect of the overloading is to cause the motor to heat up and, in the worst case, to catch on fire or to ignite nearby inflammable material.
It is one of the objects of the present invention to provide means to detect the possibility of malfunctioning of tape loading apparatus and to interrupt the supply of current to the motor that drives the apparatus, thus preventing the generation of excess heat.
Further objects will become apparent from the following description together with the drawings.